This invention relates to a double acting baulkring-type synchronizer.
Baulkring-type synchronizers for use in multi-ratio transmissions are well known. Such synchronizers include pairs of friction and jaw members for respectively synchronizing and positive clutching axially spaced apart ratio gears to a shaft, a hub rotatably fixed to the shaft and having external spline teeth slidably receiving internal spline teeth of a shift sleeve, baulkrings having blocker teeth for arresting engaging movement of the shift sleeve until synchronization is reached and for transferring a shift force from the sleeve to friction members. Such synchronizers often include pre-energizer assemblies for effecting initial engagement the friction members in response to initial engaging movement of shift sleeve. It is also known that the shift time and/or shift effort required by a vehicle operator, i.e., force applied to a shift lever, may be reduced by use of synchronizer mechanisms of the self-energizing type. A baulkring-type synchronizer of the self-energizing type may be seen by reference to U.S. Pat. No. 5,544,727, which is incorporated herein by reference.
When double acting baulkring type synchronizers are shifted from an engaged position with one ratio gear to the other ratio gear, the friction clutch of the ratio gear being disengaged may remain engaged enough to continue to transmit torque after the engagement of the friction clutch of the gear being engaged. Thereby tending to rotate the baulkrings relative to each other with damaging forces.
An object of this invention is to provide a baulkring-type synchronizer with improved friction clutch disengagement.
According to a feature of the invention, a double acting synchronizer selectively synchronizes and positive connects a shaft with either of axially spaced apart first and second drives disposed for relative rotation about an axis of the shaft and axially fixed relative thereto. The synchronizer comprises: A first element is affixed to the shaft concentric to the axis and between the drives. Jaw teeth are affixed to each drive. A friction surface is affixed to each drive. A second element is mounted for rotation with and axial movement relative to the first element. The second element has jaw teeth engagable with the jaw teeth of either of the drives in response to a to-or-fro axial engaging movement of the second element from a neutral position by a shift force. A baulkring is associated with each drive and axially movable relative to each other. Each baulkring is disposed between the first element and the associated drive and each baulkring includes a plurality of pairs of blocker surfaces affixed thereto and a friction surface engagable with the friction surface of the associated drive to produce a synchronizing torque. Blocker surfaces are axially affixed to the second element and engagable with the blocker surfaces of either baulkring in response respectively to the to-or-fro movement of the second element for preventing asynchronous engagement of the engagable jaw teeth, for transmitting the operator shift force across the engaged blocker surfaces to effect engagement of the associated friction surfaces, and for producing a torque counter to the synchronizing torque.
The synchronizer is characterized by rigid member means for disengaging the friction surface of one baulkring prior to engagement of the friction surface the other baulking in response to the second element being moved by the shift force from a position having the jaw teeth thereof engaged with the jaw teeth affixed to one drive toward a position for engaging the jaw teeth thereof with the jaw teeth affixed to the other drive The rigid member means including a plurality of circumferentially spaced apart rigid joining members each having an axially extending portion extending over a radially outer portion of each baulkring and each having radially inwardly extending first and second rigid end portions contactable with axially oppositely facing surfaces of each baulkring for preventing axial separation of the baulkrings in excess to the axially spaced apart first and second rigid end portions.